Hold a weight plate by its edge in one hand, arm resting in front of your thigh with the plate hanging vertically. Keeping your elbow nearly straight, raise the plate forward and up to about shoulder height, then lower it back down under control. Working one side at a time means you can't lean on your torso or your other arm to help finish the rep, so any twisting or hip drive shows up immediately. Switch hands once you're through with one side, and keep the plate's edge gripped firmly since it wants to rotate in your hand as you raise it.